Abstract Liver transplants are a life-saving treatment for patients, but have slow and insensitive metrics of transplant rejection. This application explores a genetically engineered cell biosensor that is pre- engrafted into a transplant in order to report and respond to early warning signals of transplant failure through the following aims: (1) In Vitro Screening of MSC Biosensors Against Plasma from Transplant Recipients, and (2) Theranostic Study Of Ex Vivo Engrafted Biosensors in Allograft Rejection Settings. These data will establish a proof-of-concept of cell biosensors for to monitor and locally treat transplanted organs with impact in basic and applied transplant biology research.